This study will test the hypothesis that kindergarten entry is a stressor that results in increased immunodeficiency and infection in HIV-infected children. The School Entry Project is an NIMH sponsored research study now in its fourth year of examining the earliest primary school experiences of the children of HIV+ mothers. During the developmentally challenging and often stressful transitions to elementary school, our study team collects data on the children and their family and social contexts. Data include measures of individual child differences in cognition, behavior and emotional and social well being as well as biological markers including pre- and post-school entry salivary cortisol levels and selected immunological assays. Family events, resources and functioning are also examined. With these data we will elucidate the school adjustment experiences of these vulnerable children who are entering school in ever-increasing numbers.